JP3435581B2 - Spark plug - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates has a central electrode in the axial hole of the hollow insulator, relates ignition plug having a characteristic method for joining the terminal and the center electrode to fasten the center electrode is there.

[0002]

2. Description of the Related Art In a method of joining a terminal having a center electrode in a shaft hole of a hollow insulator to the center electrode, conventionally, a joining method using a low melting point metal such as soldering or brazing, or providing a claw inside the terminal The nail and the center electrode are engaged with each other when the claw is screwed to the insulator, so that the terminal and the center electrode are joined to each other and electrical continuity is secured.

Conventionally, in a known first ignition plug 100 for an internal combustion engine shown in FIG. 5, a center electrode formed in a terminal is provided in order to secure electrical continuity between the center electrode 1 and the terminal 2. internal claw-like protrusions 4 several points set <br/> only to the holes 3 to be fitted, the center electrode outer diameter inner diameter of the projection 4, 0.01 m
It is set smaller by about m.

Since the inner diameter of the claw-shaped projection 4 is set to be slightly smaller than the outer diameter of the center electrode 1, when the terminal 2 is screwed into the insulator 5 after the center electrode 1 is assembled. In addition, the claw-shaped projection 4 bites into the center electrode 1, whereby electrical continuity between the terminal 2 and the center electrode 1 is secured.

In addition, another known second type as shown in FIG.
In the internal combustion engine ignition plug 110, the claw-shaped projection as described above is not provided inside the hole 3 formed in the terminal,
When the center electrode 1 is assembled to the insulator 5, due to the eccentricity between the shaft hole 50 of the insulator and the center electrode 1 which is unavoidable in production, the center electrode 1 is formed on the inner diameter side of the hole 3 formed in the terminal. Contact each other, and the contact portion 21 ensures electrical continuity between the terminal 2 and the center electrode 1.

In addition, in the conventionally known jet engine igniter plug 120 as shown in FIG. 7, the normal electric spark energy is one of the spark plugs for automobiles.
It is about 00 times, and in the method of making the terminal 2 and the center electrode 1 electrically conductive by a method such as the spark plug for an internal combustion engine described above, the conduction is sufficient to flow a large current when a spark is generated. Instead, sparks or galvanic corrosion occur at the contact area. Therefore, in order to secure sufficient electrical conductivity, it was necessary to braze or solder the terminal 2 and the center electrode 1 or the like.

[0007]

In the first spark plug 100 shown in FIG. 5, the claw-shaped projection 4 and the center electrode 1 are provided.
It is necessary to manage the difference between the outer diameters of the terminals to be as small as about 0.01 mm because the larger the bite amount when the terminal 2 is screwed into the insulator 5, the larger the screwing torque when the terminal 2 is screwed. It becomes difficult to screw it in.

As a countermeasure against this, hexagonal terminals are provided,
It may be possible to make it easier to apply the force to screw in the terminal by eliminating slippage, but by providing a hexagon, the unit price of the parts increases and the terminal becomes directional, so attach a plug cap not shown in the figure. Since it is necessary to keep the direction constant, a new problem arises in that the manufacturing cost of the spark plug 100 and the increase of man-hours when mounting the spark plug 100 on the engine lead to an increase in cost.

Further, in order to reduce the screwing torque, the material of the center electrode 1 is very soft, for example,
It needs to be made of something like annealed copper.

Therefore, dimensional regulation and material selection are very limited, and the degree of freedom in design is reduced.

In the second spark plug 110 shown in FIG. 6, the eccentricity of the center electrode 1 is not uniform, and electrical conductivity is obtained only by the contact force of the center electrode hitting the inner diameter of the inner hole 3 of the terminal. the way to ensure, when the contact force have <br/> small, at the time of discharge, with the contact surface 21, an electric spark is generated.

Unlike the electric spark in the ignition part, such an electric spark is not covered with metal around the terminal part.
Since it is not magnetically shielded, radio noise generated by electric sparks generated inside the terminal may cause malfunction of electronic components.

That is, since electric sparks in the ignition part are generated inside the metal combustion chamber, the radio noise is reduced, and therefore, there is no portion surrounding the radio noise for electronic parts as in the previous term. , Directly affect.

In the vicinity of the contact portion with the center electrode inside the terminal, the manufacturability is considered first, and it is vulnerable to electric corrosion due to the generation of electric sparks, and the contact resistance increases,
This causes an increase in the air gap due to electric corrosion, that is, an increase in the minimum required voltage required for the generation of electric sparks, resulting in a problem that the life of the plug is shortened.

In addition, in the igniter plug 120 for a jet engine shown in FIG. 7, the terminal 2 and the center electrode 1 have electrical conductivity secured by soldering, and the terminal is maintained up to the temperature at which the solder material melts in the manufacturing process. Since it is necessary to raise the temperature in the vicinity of 2 and the surrounding material must be one that does not deteriorate even at that temperature, there are restrictions on the selection of the material and the degree of freedom in design is reduced.

That is, since the insulator and the outer metal shell are usually made of ceramic and metal, there is no problem at this temperature, but in order to prevent the combustion gas from leaking from the inside of the plug, etc. Some of the materials used for the above, such as glass for sealing materials and powdered powder called talc, have poor heat resistance, which limits the use of these materials and reduces the degree of freedom in design.

In order to solve this, when a solder having a low melting point is used, and particularly in a jet engine, the temperature of the terminal portion may rise to the melting temperature of the solder having a low melting point. In some cases, the solder may melt during use, resulting in poor conduction, and the plug function may not be fulfilled.

[0018]

The present invention is intended to solve these problems and is intended to secure the electrical conductivity of the terminal and the center electrode and to increase the degree of freedom in design. , Inside the shaft hole of the hollow insulator, has a taper portion that is a small diameter portion, insert the terminal into this insulator,
A center electrode having a thin-walled pipe-shaped portion on the side of the terminal to be inserted into the insulator, the thin-walled pipe-shaped portion of the terminal being deformed along the tapered portion of the insulator, and being fitted inside the terminal. Is a spark plug in which a thin pipe-shaped portion is deformed and fastened .

[0019]

According to the invention of claims 1 to 4 , when the terminal is inserted into the insulator, the thin pipe-shaped portion of the terminal is
By deforming along the taper part that is a small diameter part provided inside the shaft hole of the insulator and tightening the center electrode inserted inside the terminal, the electrical conductivity between the center electrode and the terminal is improved. Each has its own effect .

According to the second aspect of the present invention, since the thin-walled pipe-shaped portion has the slit, the deformation of the slit facilitates the deformation of the thin-walled pipe-shaped portion and improves the fastening force with the center electrode. The range of material selection is expanded. In other words, when the thin-walled pipe-shaped part is made of a material that is strong and difficult to deform, the screw neck part may break when tightening the terminal, especially in the type that is screwed by the insulator and the screw of the terminal, By having, it is possible to prevent breakage.

According to the invention of claim 3 , since the tapered portion is provided outside the tip of the thin pipe portion of the terminal,
It becomes easier to deform along the taper portion provided inside the shaft hole of the insulator, the tightening force of the center electrode inserted and fitted inside the terminal is improved, and there is more room for material selection.

According to the invention of claim 4, the center electrode is inserted into the terminal at the same time when the terminal is assembled to the insulator. Therefore, C chamfering or R processing is performed on the inner diameter side of the tip of the thin pipe portion of the terminal. it allows insertion into the interior of the terminals of said center electrode is easily performed.

[0023]

EXAMPLES Example 1 An example of the present invention will be described with reference to FIGS. The igniter plug of the present invention has a shaft hole 50 of the insulator 5.
Has a center electrode 1, has a terminal 2 on a side 23 of a joint with an ignition lead (not shown), and has a tapered portion 52, which is a small diameter portion, inside the shaft hole of the insulator. A hole 3 for inserting the center electrode 1 including a thin pipe-shaped portion 21 is provided on the side of the terminal 2 into which the insulator 5 is inserted.

In the manufacturing process, first, the center electrode 1 and the insulator 5 are assembled to the metal outer cylinders 70 and 71. Next, the cut terminal 2 of the male screw 22 is screwed in along the female screw 51 provided on the insulator 5. Per thin pipe-like portion 21 of the pin when screwing the terminal 2 to the tapered portion 52 provided inside the axial hole of the insulator 5, further said thin pipe-like portion 21 when Yuku screwed to the tapered portion 52 of the Transform along.

On the other hand, a hole 3 into which the center electrode is inserted is formed inside the terminal 2.
Is provided, and when the terminal 2 is screwed into the hole 3,
The rear end 11 of the center electrode previously assembled is inserted. Therefore, the thin-walled pipe-shaped portion 21 is deformed along the tapered portion 52 provided inside the shaft hole of the insulator 5, so that the thin-walled pipe-shaped portion 21 is inserted into the center electrode 1 inserted in the hole 3 provided in the terminal. The tip 211 of the part bites. This ensures electrical continuity between the center electrode 1 and the terminal 2.

The outer diameter of the center electrode 1 in this embodiment is φ2.0 mm, and the thin-walled pipe-shaped portion 2 of the terminal is used.
The wall thickness of 1 was 0.3 mm and the length thereof was 3 mm. Further, the inner diameter of the hole 3 inside the terminal is φ2.1 mm, and the angle 521 of the tapered portion 52 provided inside the insulator has an angle of 30 degrees with respect to the long axis direction of the insulator.

Embodiment 2 In this embodiment, as shown in FIG. 3, slits 212 are formed at two places of the thin pipe-shaped portion 21 of the terminal. The thin-walled pipe-shaped portion is deformed by the reduction of the slit width, so this deformation occurs relatively easily, and the tip 211 of the thin-walled pipe-shaped portion is attached to the center electrode 1 inserted into the hole 3 provided in the terminal. Compared with the case without slit, the biting force is
It will be strong. In addition, in this embodiment, the slit width is 0.5 mm, and the others are the same as in the first embodiment.

Example 3 In this example, C chamfering or R processing was performed on the inner diameter side of the tip 211 of the thin pipe-shaped portion of the terminal as shown in the enlarged view of the terminal portion of the igniter plug of FIG. The smaller the deformation of the thin-walled pipe-shaped portion 21 of the terminal, the smaller the screwing amount of the terminal 2, and therefore the less the piece time in the manufacturing process and the number of steps. Therefore, in order to reduce the deformation, it is better that the difference between the outer diameter of the center electrode 1 and the inner diameter of the hole 3 provided in the terminal is smaller. However, during manufacture, the inner diameter 522 of the taper portion of the insulator and the center electrode 1 inevitably sway, so the inner diameter side of the tip 211 of the thin-walled pipe-shaped portion of the terminal is not chamfered or R-machined. Then, the tip 211 of the thin pipe portion of the terminal and the rear end 11 of the center electrode may come into contact with each other, and the terminal may not be screwed in.
In this case, as in the present example, the chamfering or the R processing is performed on the inner diameter side of the tip 211 of the thin-walled pipe-shaped portion of the terminal, so that the terminal can be smoothly screwed.

In this embodiment, the outer diameter of the center electrode 1 is φ2.0 mm and the inner diameter of the hole 3 inside the terminal is φ2.
Processing of C0.2 was performed on the inner diameter side of the tip 211 of the thin pipe portion of the terminal of 1 mm.

[Brief description of drawings]

FIG. 1 is a sectional view around a terminal portion of an igniter plug according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view around a terminal portion showing a manufacturing process in the first embodiment of the present invention.

FIG. 3 is a cross-sectional view around a terminal portion of an igniter plug according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view around a terminal portion of an igniter plug according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a conventionally known first spark plug for an internal combustion engine.

FIG. 6 is a sectional view of a conventionally known second spark plug for an internal combustion engine.

7 is a cross-sectional view of the igniter plug known jet engine.

[Explanation of symbols]

1 center electrode 2 terminal 3 hole for fitting with center electrode formed on terminal 4 hole for fitting with center electrode formed on terminal 4 claw-shaped protrusion 5 provided inside the insulator 6 brazing or soldering Attachment 21 Thin-walled pipe-shaped portion 22 Male screw 51 of terminal 51 Female screw 52 of insulator Tapered portion 100 Known first internal combustion engine ignition plug 110 Known second internal combustion engine ignition plug 120 Known jet engine igniter plug 212 Slit

Continuation of the front page (56) References JP-A-3-159087 (JP, A) JP-A-52-46239 (JP, A) JP-A-61-116788 (JP, A) Jitsukaihei 3-58890 (JP , U) Actually open 48-97520 (JP, U) Actually open 55-164794 (JP, U) Actually open 63-54266 (JP, U) Actually open 51-15677 (JP, U) JP 4-45941 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01T 13/00-21/06 H01R 4/32-4/60

Claims (4)

(57) [Claims] 1. An ignition plug for an internal combustion engine, which has a center electrode in a shaft hole of an insulator and has a terminal on a side of a joint with an ignition lead, wherein a small diameter portion is provided inside the shaft hole of the insulator. has a tapered portion which becomes, with the terminal comprises a thin-walled pipe-like portion on the side to be inserted into the insulator, has a hole for inserting a center electrode, the thin-walled pipe-shaped portion of the terminal, the is deformed along the tapered portion of the insulator, the spark plug center electrode which is inserted into the inner terminal is fastened. 2. The spark plug according to claim 1, wherein a terminal having slits at one location or at two or more locations is used in a thin pipe-shaped portion of the terminal. 3. The spark plug according to claim 1 , wherein a taper portion is provided outside the tip of the thin-walled pipe-shaped portion of the terminal. 4. A spark plug according to claim 3 which has been subjected to C chamfering or R processed into thin tubular tip inner diameter side of the terminal.